As usual my search for a topic returned everything but what I was searching for and my apologies if this has already been addressed.

Central Supply Catalog PDF Law Enforcement p. 6

Law Enforcement
If a negative Effect is rolled during a Streetwise check when determining availability of an item on the black market, the
system’s law enforcement agencies will become involved. This is normally bad news for the Traveller concerned.

If this happens, roll 2D and deduct both the Effect (apply it as a negative) and the system’s Law Level, then consult the Law
Enforcement Response table.

My impression from the text is 2D - Effect - Law Level which does not match the formula shown below

Law Enforcement Response Table
2D + Effect & Law Level

The formula I believe should 2D - Effect & Law Level or 2D - Effect - Law Level

Technically, the 2d + Effect part is correct, as the Effect in this case would be negative. Adding a negative number to a positive number (the die roll) results in a lower number. So 7 + -3 is the same as 7-3 (both result in 4). Subtracting a negative number would result in a higher number (7 - -3 = 10).

But you are also correct. You should be subtracting the Law rating, not adding it. A higher Law rating should make it more likely the authorities get involved.

Technically, the 2d + Effect part is correct, as the Effect in this case would be negative. Adding a negative number to a positive number (the die roll) results in a lower number. So 7 + -3 is the same as 7-3 (both result in 4). Subtracting a negative number would result in a higher number (7 - -3 = 10).

But you are also correct. You should be subtracting the Law rating, not adding it. A higher Law rating should make it more likely the authorities get involved.

Ultimately, it should be: 2D + Effect - Law Level.

From the source document

"If this happens, roll 2D and deduct both the Effect (apply it as a negative) and the system’s Law Level, then consult the Law
Enforcement Response table."

The text above appears to me at first glance as an equation of 2D - (-Effect) - Law Level or 2D + Effect - Law. Since the Law Enforcement Response is triggered by a failed check the my second thought is 2D - Effect - Law Level.

Looking at the equation shown on the table of 2D + Effect & Law Level means 2D + Effect + Law Level which does not appear to match the text.

The equation of 2D + Effect - Law Level does not indicate that the Effect is a negative value per the instruction in the text. The clearest equation I feel is 2D - Effect - Law Level.